U.S. patent application number 11/001200 was filed with the patent office on 2005-06-09 for administration of growth factors for neurogenesis and gliagenesis.
This patent application is currently assigned to MEDTRONIC INC.. Invention is credited to Shafer, Lisa L..
Application Number | 20050123526 11/001200 |
Document ID | / |
Family ID | 34637002 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050123526 |
Kind Code |
A1 |
Shafer, Lisa L. |
June 9, 2005 |
Administration of growth factors for neurogenesis and
gliagenesis
Abstract
Devices and methods for treating diseases associated with loss
of neuronal function by cell replacement therapy are described. The
methods are designed to promote proliferation, differentiation,
migration, or integration of exogenous stem cells transplanted into
the central nervous system (CNS). A therapy, such as an electrical
signal or a stem cell enhancing agent, or a combination of
therapies, is applied to a CNS region having damaged neuronal
tissues, into which region exogenous stem cells are transplanted. A
therapy may also be applied to a second region of the CNS to which
neurons from the damaged CNS region are expected to project. The
exogenous stem cells may be transfected with an electrically
responsive genetic construct comprising an electrically responsive
promoter and a target gene. Expression of the target gene, which
may encode a gene product that promotes proliferation,
differentiation, migration, or integration of the exogenous stem
cell, may be closely controlled by application of an electrical
signal.
Inventors: |
Shafer, Lisa L.;
(Stillwater, MN) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MS-LC340
MINNEAPOLIS
MN
55432-5604
US
|
Assignee: |
MEDTRONIC INC.
Minneapolis
MN
|
Family ID: |
34637002 |
Appl. No.: |
11/001200 |
Filed: |
December 1, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60526405 |
Dec 1, 2003 |
|
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|
60526318 |
Dec 1, 2003 |
|
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Current U.S.
Class: |
424/93.21 ;
424/143.1; 514/17.8; 514/18.1; 514/8.1; 514/8.2; 514/8.4; 514/8.6;
514/8.9; 514/9.1; 514/9.6; 607/47 |
Current CPC
Class: |
A61N 1/36082 20130101;
A61N 1/326 20130101 |
Class at
Publication: |
424/093.21 ;
514/012; 607/047; 424/143.1 |
International
Class: |
A61K 048/00; A61N
001/18 |
Claims
What is claimed is:
1. Therapeutic delivery system comprising: a housing; a electrical
signal generator disposed in the housing; genetically engineered
stem cells comprising a target gene operably coupled to an
electrically responsive promoter, the cells being operably coupled
with the electrical signal generator; a pump disposed in the
housing; a reservoir operably coupled to the pump; and one or more
stem cell enhancing agents disposed in the reservoir, the one or
more stem cell enhancing agents configured to promote the
proliferation, migration, differentiation, or integration of a stem
cell.
2. The device of claim 1, wherein at least one of the one or more
stem cell enhancing agents is selected from the group consisting of
GDNF, BDNF, FGF, VEGF, NT-3, TGF-alpha, EGF, IGF-1, CNTF, a
glutamate receptor agonist, a GABA receptor antagonist, and an
anti-Nogo-A antiboby.
3. The system of claim 1, further comprising: a lead operably
coupled to the pulse generator; and a catheter operably coupled to
the pump.
4. The system of claim 1, wherein the target gene encodes a gene
product that promotes the proliferation, differentiation,
migration, or integration of the genetically altered stem cell.
5. The system of claim 4, wherein the target gene encodes CNTF,
GDNF, BDNF, FGF, VEGF, NT-3, TGF-alpha, TGF-beta, EGF, IGF-1, NT-4,
NT-5, EGF, CNTF, SCF, c-fos, NeuroD2, pax6, emx2, SHH, noggin, IL-3
FL, PDGF, FL, Tpo, IL-6, IL-11, or an active derivative or fragment
thereof.
6. A method for treating a disease associated with a loss of
neuronal function in a subject in need thereof, the method
comprising: transplanting an exogenous stem cell to a first CNS
region, the first CNS region comprising damaged neuronal tissue;
implanting a lead in the subject such that an electrode of the lead
is positioned in the first CNS region; implanting a catheter in the
subject such that a delivery region of the catheter is positioned
in the first CNS region; applying an electrical signal to first CNS
region to promote proliferation, differentiation, migration, or
integration of the exogenous stem cell; and delivering a first stem
cell enhancing agent to the first CNS region to promote
proliferation, differentiation, migration, or integration of the
exogenous stem cell.
7. The method of claim 6, wherein the exogenous stem cell comprises
an electrically responsive nucleic acid construct, the construct
comprising an electrically responsive promoter and a target gene
encoding a gene product capable of promoting the proliferation,
differentiation, migration, or proliferation of the exogenous stem
cell.
8. The method of claim 7, wherein the applying the electrical
signal to first CNS region comprises applying an electrical signal
to the first CNS region to induce expression of the target gene
product.
9. The method of claim 7, wherein the target gene product is
selected from the group consisting of a CNTF, GDNF, BDNF, FGF,
VEGF, NT-3, TGF-alpha, TGF-beta, EGF, IGF-1, NT-4, NT-5, EGF, CNTF,
SCF, c-fos, NeuroD2, pax6, emx2, SHH, noggin, IL-3 FL, PDGF, FL,
Tpo, IL-6 and IL-1.
10. The method of claim 7, wherein the target gene product is an
active fragment or derivative of CNTF, GDNF, BDNF, FGF, VEGF, NT-3,
TGF-alpha, TGF-beta, EGF, IGF-1, NT-4, NT-5, EGF, CNTF, SCF, c-fos,
NeuroD2, pax6, emx2, SHH, noggin, IL-3 FL, PDGF, FL, Tpo, IL-6 or
IL-11.
11. The method of claim 6, wherein the stem cell enhancing agent is
selected from the group consisting of a growth factor, a
chemoattractant, a neurotransmitter receptor agonist or antagonist,
a transcription factor, and an inhibitor of a growth inhibitory
molecule.
12. The method of claim 11, wherein the growth factor is selected
from the group consisting of CNTF, GDNF, BDNF, FGF, VEGF, NT-3,
TGF-alpha, EGF, IGF-1, NT-4, NT-5, EGF, CNTF, and SCF.
13. The method of claim 11, wherein the chemoattractant is selected
from the group consisting of SDF-1, fractalkine, GRO-.alpha., IL-8,
MIP-1a, MIP-1b, MCP-1, MCP-2, MCP-3, GRO-a, GRO-b, GRO-g, RANTES,
and eotaxin.
14. The method of claim 11, wherein the neurotransmitter receptor
agonist is a glutamate receptor agonist, an alpha 1-adrenergic
agonist, an alpha 2-adrenergic agonist, a serotonergic agonist, a
dopaminergic agonist, or a GABAergic agonist.
15. The method of claim 11, wherein the neurotransmitter receptor
antagonist is a GABA receptor antagonist an alpha 1-adrenergic
antagonist, an alpha 2-adrenergic antagonist, a serotonergic
antagonist, a dopaminergic antagonist, or a GABAergic
antagonist.
16. The method of claim 11, wherein the transcription factor is
selected fromteh group consisting of Pax6, EMX2, SHH, a member of
the NeuroD family, a member of the CREB family, c-fos, myocyte
enhancer factor-2 (MEF-2) and basic helix-loop-helix (bHLH)
transcription factors.
17. The method of claim 11, wherein the inhibitor of a growth
inhibitory molecule is an inhibitor of amino NogoR receptor signal
transduction, a Rho signal transduction inhibitor, and Arginase
I.
18. The method of claim 6, wherein the disease is selected from the
group consisting of Parkinson's disease, Alzheimer's disease,
spinal cord injury, traumatic brain injury, and stroke.
19. The method of claim 18, wherein the disease is Parkinson's
disease and the first CNS region is the substantia nigra.
20. The method of claim 18, wherein the disease is Alzheimer's
disease and the first CNS region is the forebrain, nucleus basalis
of Meynert, neocortical region, medial temporal region, locus
ceoruleus, or raphe nucleus.
21. The method of claim 18 wherein the disease is spinal cord
injury and the first CNS region is intrathecal at the level of the
injury.
22. The method of claim 6, further comprising: implanting a therapy
delivery element comprising a therapy delivery region in the
subject and positioning the therapy delivery region of the therapy
delivery element in a second CNS region to which neurons from the
first CNS region are predicted to project; and applying a therapy
to the second CNS region via the therapy delivery region to promote
projections of the neurons from the first CNS region to the second
CNS region.
23. The method of claim 22, wherein the projections comprise
projections of neurons derived from the exogenous stem cell.
24. The method of claim 22, wherein the projections comprise
projections of neurons other than neurons derived from the
exogenous stem cell.
25. The method of claim 22, wherein applying therapy to the second
CNS region comprises delivering a stem cell enhancing agent.
26. The method of claim 25, wherein the stem cell enhancing agent
is selected from the group consisting of anti-Nogo-A antibody, a
p75ntr antagonist, a Rho signal transduction inhibitor, and a
nogo-66 receptor antagonist, NGF, GDNF, IGF-1, CNTF, and BDNF.
27. The method of claim 22, wherein the disease is Parkinson's
disease and the second CNS region comprises the putamen.
28. The method of claim 27, wherein the third therapy comprises
GDNF.
29. The method of claim 22, wherein the disease is Alzheimer's
disease and the second CNS region comprises the cortex, basal
forebrain or nucleus basalis of meynert.
30. The method of claim 29, wherein the third therapy comprises
NGF.
31. The method of claim 22, wherein the disease is spinal cord
injury and the second CNS region comprises a spinal location where
the injured neurons typically send projections.
32. The method of claim 31, wherein the third therapy comprises a
stem cell enhancing agent selected from the group consisting of
GDNF, BDNF, and VEGF.
33. The method of claim 6, further comprising intraventricularly or
intrathecally delivering a second stem cell enhancing agent, the
second stem cell enhancing agent being the same or different than
the first stem cell enhancing agent.
34. A method for treating a disease associated with a loss of
neuronal function in a subject in need thereof, the method
comprising: transplanting an exogenous stem cell to a first CNS
region, the first CNS region comprising damaged neuronal tissue;
implanting a first therapy delivery element comprising a therapy
delivery region in the subject and positioning the therapy delivery
region of the first therapy delivery element in the first CNS
region; implanting a second therapy delivery element comprising a
therapy delivery region in the subject and positioning the therapy
delivery region of the second therapy delivery element in a second
CNS region to which neurons from the first CNS region are predicted
to project; applying a first therapy to the first CNS region via
the therapy delivery region of the first therapy delivery element
to promote proliferation, differentiation, migration, or
integration of the exogenous stem cell; and applying a second
therapy to the second CNS region via the therapy delivery region of
the second therapy delivery element to promote projections of the
neurons from the first CNS region to the second CNS region. wherein
the first and second therapy are the same or different.
35. The method of claim 34, wherein the exogenous stem cell
comprises an electrically responsive nucleic acid construct, the
construct comprising an electrically responsive promoter and a
target gene encoding a gene product capable of promoting the
proliferation, differentiation, migration, or proliferation of the
exogenous stem cell.
36. The method of claim 35, wherein the applying the first therapy
to the first CNS region comprises applying an electrical signal to
the first CNS region to induce expression of the target gene
product.
37. The method of claim 35, wherein the target gene product is
selected from the group consisting of a CNTF, GDNF, BDNF, FGF,
VEGF, NT-3, TGF-alpha, TGF-beta, EGF, IGF-1, NT-4, NT-5, EGF, CNTF,
SCF, c-fos, NeuroD2, pax6, emx2, SHH, noggin, IL-3 FL, PDGF, FL,
Tpo, IL-6 and IL-1.
38. The method of claim 35, wherein the target gene product is an
active fragment or derivative of CNTF, GDNF, BDNF, FGF, VEGF, NT-3,
TGF-alpha, TGF-beta, EGF, IGF-1, NT-4, NT-5, EGF, CNTF, SCF, c-fos,
NeuroD2, pax6, emx2, SHH, noggin, IL-3 FL, PDGF, FL, Tpo, IL-6 or
IL-1.
39. The method of claim 34, wherein the projections comprise
projections of neurons derived from the exogenous stem cell.
40. The method of claim 34, wherein the projections comprise
projections of neurons other than neurons derived from the
exogenous stem cell.
41. The method of claim 34, further comprising intraventricularly
or intrathecally delivering a stem cell enhancing agent to promote
the proliferation, differentiation, migration, or integration of
the exogenous stem cell or a cell derived therefrom.
42. The method of claim 34, wherein at least one of the first and
second therapies comprise a stem cell enhancing agent.
43. The method of claim 42, wherein the stem cell enhancing agent
is selected from the group consisting of a growth factor, a
chemoattractant, a neurotransmitter receptor agonist or antagonist,
and an inhibitor of a growth inhibitory molecule.
44. The method of claim 43, wherein the growth factor is selected
from the group consisting of CNTF, GDNF, BDNF, FGF, VEGF, NT-3,
TGF-alpha, EGF, IGF-1, NT-4, NT-5, EGF, CNTF, and SCF.
45. The method of claim 43, wherein the chemoattractant is selected
from the group consisting of SDF-1, fractalkine, GRO-a, IL-8,
MIP-1a, MIP-1b, MCP-1, MCP-2, MCP-3, GRO-a, GRO-b, GRO-g, RANTES,
and eotaxin.
46. The method of claim 43, wherein the neurotransmitter receptor
agonist is a glutamate receptor agonist, an alpha 1-adrenergic
agonist, an alpha 2-adrenergic agonist, a serotonergic agonist, a
dopaminergic agonist, or a GABAergic agonist.
47. The method of claim 43, wherein the neurotransmitter receptor
antagonist is a GABA receptor antagonist an alpha 1-adrenergic
antagonist, an alpha 2-adrenergic antagonist, a serotonergic
antagonist, a dopaminergic antagonist, or a GABAergic
antagonist.
48. The method of claim 43, wherein the inhibitor of a growth
inhibitory molecule is anti-Nogo-A antibody, a p75ntr antagonist, a
Rho signal transduction inhibitor, and a nogo-66 receptor
antagonist.
49. The method of claim 34, wherein the disease is selected from
the group consisting of Parkinson's disease, Alzheimer's disease,
spinal cord injury, traumatic brain injury, and stroke.
50. The method of claim 49, wherein the disease is Parkinson's
disease and the first CNS region is the substantia nigra.
51. The method of claim 49, wherein the disease is Alzheimer's
disease and the first CNS region is the forebrain, nucleus basalis
of Meynert, neocortical region, medial temporal region, locus
ceoruleus, or raphe nucleus.
52. The method of claim 49, wherein the disease is spinal cord
injury and the first CNS region is intrathecal at the level of the
injury.
53. The method of claim 34, wherein the applying the second therapy
to the second CNS region comprises delivering a stem cell enhancing
agent to the second CNS region.
54. The method of claim 53, wherein the stem cell enhancing agent
is selected from the group consisting of anti-Nogo-A antibody, a
p75ntr antagonist, a Rho signal transduction inhibitor, and a
nogo-66 receptor antagonist, NGF, GDNF, IGF-1, CNTF, and BDNF.
55. The method of claim 34, wherein the disease is Parkinson's
disease and the second CNS region comprises the putamen.
56. The method of claim 55, wherein the second therapy comprises
GDNF.
57. The method of claim 34, wherein the disease is Alzheimer's
disease and the second CNS region comprises the cortex, basal
forebrain or nucleus basalis of meynert.
58. The method of claim 57, wherein the second therapy comprises
NGF.
59. The method of claim 34, wherein the disease is spinal cord
injury and the second CNS region comprises a spinal location where
the injured neurons typically send projections.
60. The method of claim 59, wherein the third therapy comprises a
stem cell enhancing agent selected from the group consisting of
GDNF, BDNF, and VEGF.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of priority from
provisional applications Ser. Nos. 60/526,405 and 60/526,318, both
filed on Dec. 1, 2003, which provisional applications are each
incorporated by reference herein in their respective
entireties.
BACKGROUND
[0002] Over the past several decades, the concept of neurological
tissue grafting or exogenous stem cell transplantation has been
investigated for its potential to treat neurodegenerative disease
such as Parkinson's disease. Stem cell technology continues to
evolve rapidly. Current approaches have resulted in some
therapeutic successes but the establishment of long-term functional
replacement is debatable and variable. In many cases it appears
that the transplanted cells do not form or maintain the fully
functional contacts essential for cell survival. The transplanted
cell may fail at any given step in the pathway to becoming a
functional replacement cell namely: proliferation, differentiation,
migration or integration.
[0003] Some researchers have attempted to drive the differentiation
of stem cells in vitro using various growth factors and
differentiation factors prior to implanting the cells. Others have
attempted to drive the differentiation of stem cells in vivo, after
they have been implanted. However, these methods have generated
very little in the way of therapeutic successes to date. In order
to study the mechanisms involved in stem cell proliferation,
differentiation, migration and integration, researchers can
transfect exogenous stem cells in vitro with gene sequences thought
to be involved in these processes. Using transfected exogenous stem
cells to determine gene function has served as a valuable research
tool but has not been applied as a therapeutic strategy to the same
degree. Research to date suggests that several growth and
differentiation factors may be involved in these processes and the
particular agent or mix of several depends on the type of cell
desired.
[0004] Examples of factors that encourage proliferation/expansion
Interleukin-3 (IL-3), stem cell factor (SCF), and Flt-3 ligand
(FL), Platelet-derived growth factor (PDGF), and epidermal growth
factor(EGF), fibroblast growth factor-2 (FGF-2). A cocktail of
several may be applied. For example, neuronal precursor cells have
been expanded in the presence of both EGF and FGF-2. A specific
example is provided by Lazzari et al. (2001) wherein, the highest
expansion of cord blood HSC was obtained with a cocktail containing
FL, thrombopoeietin (Tpo), IL-6 and IL-11.
[0005] Transcription factors such as Pax6 and Emx2 may be required
for proliferation and patterning during neuronal development. Sonic
hedgehog (SHH) is well known for its control of numerous processes
during development as well as acting as a mitogen for embryonic
neural stem cells. SHH may induce proliferation of adult stem
cells. In the adult CNS, actions of BMP and noggin are believed to
regulate the balance between neurons and astrocytes. Such gene
sequences may be incorporated in exogenous stem cells via
transfection prior to implantation.
[0006] Further, transforming growth factor-beta (TGF-b) family
members have been demonstrated to have differentiation effects on
ES cells (Schuldiner M. 2000) and neural crest stem cell
differentiation (Shah N. M. (1996); White P. M. (2001)). Other
agents that contribute to differentiation and that may be
administered to optimize the microenvironment are Wnt factors,
integrins, and extracellular matrix components. A mix of factors
may be applied to differentiate a group of stem cells into a
particular type of neuron, after the cells were first encouraged to
proliferate: For example, FGF-2, ascorbic acid, sonic hedgehog
(SHH) and FGF-8 have been used to differentiate mouse ES cells to
obtain dopaminergic and serotonergic neurons (Lee S. M. 2000).
[0007] Although extensive research continues in the areas of in
vitro transfection of exogenous stem cells, very little has been
reported on methods to control and regulate these exogenous
transplanted cells, and in particular the expression of transfected
elements in vivo. Researchers have taken advantage of inherent DNA
sequences found upstream of a gene, which regulate the expression
of the gene under different physiological conditions. To this end,
recombinant elements have been developed to effectively introduce
and express genes in many cell types. Several protocols have been
published which have focused on pharmacologically-based control of
gene expression. Generally the basis of these methods relies on the
presence of a pharmacological agent to control the activation of
the DNA promoter sequences. An example of this is the
Tet-On/Tet-Off gene expression system, which is commercially
available. The presence or absence of tetracycline or doxycycline
will activate the promoter responsible for turning on gene
expression. Administration of the activating pharmacological agent
is generally done systemically in an effort to deliver the
affecting transcription to the site of the action. Although
technically effective at inducing gene expression, the possibility
exists that systemic administration of pharmacological agents in
vivo can result in unwanted side effects or toxicity in surrounding
tissues. Further, because pharmacological agents reside in the body
over a period of time, often for days, regulation of the gene
promoter sequence is not tightly coupled from the time the
activating agent is given until it is eliminated from the body.
[0008] WO 02/49669 discloses the controlled delivery of therapeutic
gene products regulated in a patient via an electrical device. In
WO 02/49669, an electrical pulse generator, e.g., a pacemaker, is
used to closely modulate the time, frequency, and delivery amount
of a given therapeutic product and to closely define the locus of
delivery, such that tissues containing genetically engineered cells
that have received electrically responsive promoter elements direct
the expression of a therapeutic product upon receiving electrical
stimulation. A system described in WO 02/49669 utilizes an
electrical stimulus (provided by an electrical pulse generator) as
a means to control the expression of electrically responsive
promoters (ERPs) that have been transplanted or incorporated into
the tissue of a mammal. The target gene of interest is operably
linked to an electrically responsive promoter sequence to provide
controlled expression by the ability to closely regulate the
electrical stimulus. The ERP gene constructs can be delivered by
standard gene transfection methods to cells grown in culture and
then implanted into the patient, or delivered directly to tissues
or cells in vivo through the use of an appropriate gene delivery
vector (viral or non-viral). Implantable electrodes operably
coupled to the pulse generator can then be used to electrically
stimulate at a defined locus the electrically responsive promoters
in transfected or transplanted cells, which consequently results in
the controlled expression of operably linked DNA sequences.
[0009] The present disclosure relates to the use of exogenous stem
cells, whether or not transfected with an ERP gene construct, as
cell replacement therapy for CNS disorders. Such use of exogenous
stem cells coupled with application of an electrical signal and a
stem cell enhancing agent configured to promote proliferation,
differentiation, migration, or integration of the exogenous stem
cell has not been described. Additionally, the further application
of a therapy to a CNS location to which transplanted exogenous stem
cells or neuronal derivatives thereof are predicted to project have
not been described.
SUMMARY
[0010] The present disclosure describes improved devices and
methods configured for using exogenous stem cells, whether or not
transfected with an ERP gene construct, as cell replacement therapy
for CNS disorders. This disclosure describes the combination of
electrical and chemical therapies to optimize the proliferation,
differentiation, migration, or integration of exogenous stem cells.
In addition, this disclosure describes administration of stem cell
enhancing agents or electrical signals at more than one location to
enhance treatment of disorders associated with loss of neuronal
function.
[0011] In an embodiment, the invention provides a therapy delivery
system. The therapy delivery system comprises a housing. An
electrical signal generator, such as a pulse generator, and a pump
are disposed within the housing. A reservoir is operably coupled to
the pump and contains one or more stem cell enhancing agents, such
as a growth factor. The system further comprises genetically
engineered stem cells comprising a target gene operably coupled to
an electrically responsive promoter. The target gene may encode a
gene product that promotes the proliferation, differentiation,
migration, or integration of the genetically altered stem cells.
The cells are operably coupled with the electrical signal
generator.
[0012] An embodiment of the invention provides a method for
treating a disease associated with loss of neuronal function in a
subject in need thereof. The method comprises transplanting an
exogenous stem cell to a first CNS region that comprises damaged
neuronal tissue. The exogenous stem cell may comprise an
electrically responsive nucleic acid construct. The construct
comprises an electrically responsive promoter and a target gene
encoding a gene product capable of promoting the proliferation,
differentiation, migration, or proliferation of the exogenous stem
cell. The method further comprises implanting a lead in the subject
such that an electrode of the lead is positioned in the first CNS
region. An electrical signal is applied via the electrode to the
first CNS region. The electrical signal is configured to promote
proliferation, differentiation, migration, or integration of the
exogenous stem cell. The promotion of proliferation,
differentiation, migration, or integration may occur by applying an
electrical signal configured to induce expression of the target
gene product. The method further comprises implanting a catheter in
the subject such that a delivery region of the catheter is
positioned in the first CNS region. A first stem cell enhancing
agent is applied to the first CNS region via the delivery region.
The stem cell enhancing agent is capable of promoting
proliferation, differentiation, migration, or integration of the
exogenous stem cell. The method may further comprise implanting a
therapy delivery element comprising a therapy delivery region in
the subject and positioning the therapy delivery region of the
therapy delivery element in a second CNS region to which neurons
from the first CNS region are predicted to project. A therapy may
be applied to the second CNS region via the therapy delivery region
to promote projections of the neurons from the first CNS region to
the second CNS region. The method may further comprise
intraventricularly or intrathecally delivering a second stem cell
enhancing agent. The second stem cell enhancing agent may be the
same or different than the first stem cell enhancing agent.
[0013] In an embodiment, the invention provides a method for
treating a disease associated with loss of neuronal function in a
subject in need thereof. The method comprises transplanting an
exogenous stem cell to a first CNS region that comprises damaged
neuronal tissue. The exogenous stem cell may comprise an
electrically responsive nucleic acid construct that comprises an
electrically responsive promoter and a target gene encoding a gene
product capable of promoting the proliferation, differentiation,
migration, or proliferation of the exogenous stem cell. The method
further comprises implanting a first therapy delivery element, such
as a lead or catheter, comprising a therapy delivery region, such
as an electrode or infusion section, in the subject and positioning
the therapy delivery region of the first therapy delivery element
in the first CNS region. A first therapy is applied to the first
CNS region via the therapy delivery region of the first therapy
delivery element to promote proliferation, differentiation,
migration, or integration of the exogenous stem cell. The first
therapy may comprise an electrical signal that is capable of
inducing expression of the target gene product. The method further
comprises implanting a second therapy delivery element comprising a
therapy delivery region in the subject and positioning the therapy
delivery region of the second therapy delivery element in a second
CNS region to which neurons from the first CNS region are predicted
to project. A second therapy is applied to the second CNS region
via the therapy delivery region of the second therapy delivery
element to promote projections of the neurons from the first CNS
region to the second CNS region. The first and second therapy are
the same or different. The method may further comprise
intraventricularly or intrathecally delivering a stem cell
enhancing agent to promote the proliferation, differentiation,
migration, or integration of the exogenous stem cell or a cell
derived therefrom.
[0014] One or more embodiments of the invention provide advantages
over existing devices and methods for treating diseases associated
with diminished neuronal function. For example, the combined use of
electrical signals and stem cell enhancing agents should prove more
efficacious than either alone for cell replacement therapy and
treatment of diseases associated with loss of neuronal function.
The combination of electrical signals and soluble chemical agents
should enhance the proliferation, migration, differentiation, or
integration of exogenous stem cells. The deficiencies of
application of only electrical or only chemical therapies at only
one location may be overcome using the description provided herein.
In addition, the use of electrically responsive nucleic acid
constructs comprising target genes encoding for products that are
capable of proliferation, migration, differentiation, or
integration of the exogenous stem cells should prove to further
enhance the therapy. The addition of additional therapy at CNS
locations to which neurons from damaged tissue, in which exogenous
stem cells are transplanted, project may serve as yet another
advantage over existing therapies. These and other advantages will
become apparent to one of skill in the art upon reading the
disclosure presented herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a drawing of a therapy delivery system adapted to
deliver therapy to a subject's brain.
[0016] FIG. 2 is a drawing of an implantable therapy delivery
system adapted to deliver therapy to a subject's brain.
[0017] FIG. 3 is a drawing of a pulse generator therapy system.
[0018] FIG. 4 is a drawing of a pump system for delivering a
therapeutic agent.
[0019] FIG. 5 is an illustration of therapeutic elements adapted to
deliver therapy to two different brain regions, one region being a
region containing damaged nervous tissue into which an exogenous
stem cell is transplanted, the other representing a region to which
neurons from the damaged region are predicted to project.
[0020] FIGS. 6-12 are flow charts illustrating various methods for
treating a disease associated with loss of neuronal function.
[0021] FIG. 13 is a drawing of a therapy delivery device coupled to
a therapy delivery element.
[0022] FIG. 14 is a drawing of a therapy delivery device coupled to
two therapy delivery elements.
[0023] FIG. 15 is a drawing of a therapy delivery device having two
therapy delivery units, each coupled to a therapy delivery
element.
[0024] The drawings are not necessarily to scale.
DETAILED DESCRIPTION
[0025] In the following descriptions, reference is made to the
accompanying drawings that form a part hereof, and in which are
shown by way of illustration several specific embodiments of the
invention. It is to be understood that other embodiments of the
present invention are contemplated and may be made without
departing from the scope or spirit of the present invention. The
following detailed description, therefore, is not to be taken in a
limiting sense.
[0026] Definitions
[0027] All scientific and technical terms used in this application
have meanings commonly used in the art unless otherwise specified.
The definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0028] As used herein, "subject" means a living being having a
nervous system, to which living being a device or method of this
disclosure is applied. "Subject" includes mammals such as mice,
rats, pigs, cats, dogs, horses, non-human primates and humans. A
subject may be suffering from or at risk of a disease or
condition.
[0029] As used herein, the terms "treat", "therapy", and the like
are meant to include methods to alleviate, slow the progression,
prevent, attenuate, or cure the treated disease.
[0030] As used herein, "disease associated with loss of neuronal
function" means a disease, disorder, condition, and the like
resulting from impairment of nervous tissue function. The
impairment may result from damage to nervous tissue, such as a
neuron or glial cell. Nervous tissue may be damaged genetically or
through infection, disease, trauma, and the like. As used herein,
"repairing damaged neural tissue" means improving, restoring,
replacing the function of a damaged neuron. A neuron may be damaged
genetically or through infection, disease, trauma, and the
like.
[0031] As used herein, "promoting neurogenesis" refers to a series
of events (including proliferation of a neural precursor or stem
cell) that results in the appearance of a new neuron.
[0032] As used herein, "exogenous stem cell" means stem cells that
are transplanted into a subject. Exogenous stem cells include
multipotent, totipotent, pluripotent stem cells that are present in
an organ or tissue of a subject. Such cells are capable of giving
rise to a fully differentiated or mature cell types. A stem cell
may be a bone marrow-derived stem cell, autologous or otherwise, a
neuronal stem cell, an embryonic stem cell. A stem cell may be
nestin positive. A stem cell may be a hematopoeietic stem cell. A
stem cell may be a multi-lineage cell derived from epithelial and
adipose tissues, umbilical cord blood, liver, brain or other
organ.
[0033] The term "genetically engineered cell(s)" means cells that
have had defined segments of nucleic acid purposefully introduced
into the cell. The term "genetically engineered cell" is not meant
to be limited by the means of introduction of the nucleic acid
unless specifically so indicated.
[0034] The term "operably linked", as used herein, denotes a
relationship between a regulatory region (typically a promoter
element, but may include an enhancer element) and the coding region
of a gene, whereby the transcription of the coding region is under
the control of the regulatory region. As used herein, "operably
linked" refers to a juxtaposition of transcriptional regulatory
elements such that the transcriptional function of the linked
components can be performed. Thus, an ERP promoter sequence
"operably linked" to a coding sequence refers to a configuration
wherein the promoter sequence promotes expression (or inhibits the
expression if a negative regulatory element) of the gene sequence
upon electrical stimulation.
[0035] "Operably coupled", in the context of a electrical signal
generator and a tissue, refers to the transference of an electrical
stimulus by an electrical signal generator to a tissue. A signal
generator operably coupled with genetically engineered cells as
described herein refers to a configuration where an electrical
stimulus is delivered to the tissue area containing genetically
engineered cells to cause expression of an operably linked target
gene. Usually the signal is delivered from the signal generator
through leads to electrodes in contact with the tissue.
[0036] An "electrically responsive promoter" or "ERP" is a promoter
that contains a genetically engineered electrically responsive
element that modulates transcription of an operably linked target
gene in a cell upon the delivery of an electrical stimulus.
Modulated transcription may be positive or negative, and may change
the relative transcriptional amount over time by an amount that is
equal to or approximately 2, 4, 6, 10, 20, 50, 100, or 1000 fold or
greater than unstimulated cells over 1, 2, 4, 8, 16, 24, 48, or 72
hours. In one embodiment the ERP promoter is an any promoter. The
term "promoter" refers to a nucleic acid sequence that directs
transcription, for example, of DNA to RNA. As referred to herein
the promoter includes the 5' flanking sequences that promote
transcription. A promoter may contain several regulatory sequences.
A constitutive promoter generally operates at a constant level and
is not regulatable. The ERP promoters of the discussed herein can
be induced by electrical signals.
[0037] As used herein, "electrically responsive nucleic acid
construct" refers to a nucleic acid sequence comprising an
electrically responsive promoter operably linked to a target gene
such that the target gene can be expressed upon delivery of an
appropriate electrical signal to the cell.
[0038] Delivery of Therapy
[0039] Referring to FIG. 13, a therapy delivery device 100 may be
operably coupled to therapy delivery element 110. A therapy
delivery region (not shown) of therapy delivery element 110 may be
positioned in a subject's centeral nervous system (CNS) to deliver
a therapy. The therapy may be a therapeutic agent or an electrical
signal. Therapy delivery element 110 may be a catheter or a lead,
and therapy delivery region may be an infusion region of a catheter
or an electrode.
[0040] Referring to FIG. 1, a therapy delivery region 115 of a
therapy delivery element 22 may be positioned to deliver therapy
within a brain region of a subject. Therapy delivery region 115 is
shown at distal portion of therapy delivery element 22, but it will
be understood that therapy delivery region 115 may be located at
any position along therapeutic element 22. The therapy delivery
element 22 may be coupled to a therapy delivery device 10. The
device 10 may be, e.g., a signal generator or a pump for delivering
a therapeutic agent. The device 10 may be implantable. There may be
more than one therapy delivery element 22 coupled to the device 10.
An individual delivery element 22 may be divided into two portions
22A and 22B that may be implanted into the brain bilaterally.
Alternatively, a second device 10 and therapeutic element may be
used to deliver therapy to a corresponding brain region in a second
brain hemisphere.
[0041] Referring to FIG. 14, therapy delivery device 200,100
operably coupable to two therapy delivery elements 110, 120, 22 is
shown. It will be understood that therapy delivery device 200,100
may be coupled to more than two therapy delivery elements 110, 120,
22. As shown in FIG. 15, therapy delivery device 200,100 may have
two therapy delivery units 210, 220, which may be the same or
different. For example, therapy delivery units 210, 220 may both
comprise electrical signal generators, may both comprise pump
mechanisms, or one may comprise a signal generator and one may
comprise a pump mechanism. Devices 200, 100 comprising a
combination of a electrical signal generator and an a pumping
mechanism may take the form of a device described in, e.g., U.S.
Pat. No. 5,119,832, U.S. Pat. No. 5,423,877 or U.S. Pat. No.
5,458,631, each of which are hereby incorporated herein by
reference in their entireties. It will be understood that device
200, 100 may have more than two delivery units 210, 220.
[0042] Referring to FIG. 2, device 200, 100, 10 may be implanted in
a human body 120. The device 200, 100, 10 may be implanted in the
location shown or any other location suitable for the coupled
therapeutic element 120, 110, 22 to deliver therapy to a region of
the CNS. Such other suitable locations include the abdomen, the
cranium, and the neck. Therapy delivery element 120, 110, 22 may be
divided into twin portions 22A and 22B that are implanted into the
brain bilaterally. Alternatively, portion 22B may be supplied with
therapy from a separate element 120, 110, 22) and device 200, 100,
10.
[0043] Electrical Signal
[0044] In an embodiment of the invention, an electrical signal is
applied to a region of a subject's CNS. The CNS region may be,
e.g., a brain region in which an exogenous stem cell is
transplanted, a brain region containing damaged nervous tissue, a
brain region neurons from a brain region containing damaged nervous
tissue are predicted to send projections, and the like. An
"electrical signal" refers to an electrical or electromagnetic
signal. In an embodiment, the signal has a pulse width, a
frequency, an amplitude, a polarization, and a duration. An
electrical signal may be depolarizing, may be hyperpolarizing, may
increase the likelihood that a neuron will undergo an action
potential, or may decrease the likelihood that a neuron will
undergo an action potential. For example, a depolarizing signal may
be a threshold or subthreshold (i.e., not sufficient to cause a
neuron to undergo an action potential) signal. An electrical signal
may be produced by any means suitable for application of the signal
to a region of the subject's CNS. In an embodiment, the electrical
signal is generated by a pulse generator. The pulse generator may
be implantable.
[0045] Referring to FIG. 3, a pulse generator system 300 includes a
pulse generator 310 and one or more leads 320. Any suitable pulse
generator 310 and lead 320 may be used in accordance with various
embodiments of the invention. A suitable pulse generator 310
includes Medtronic Model 3625 test stimulator. A suitable lead 320
includes any of the Medtronic leads sold with the Model 3625, such
as Model YY005093 IR or other custom made leads. Lead 320 is
electrically coupled to pulse generator 310. A proximal portion 330
of the lead 320 is coupled to the pulse generator. A distal portion
340 of the lead 320 may be positioned to apply an electrical signal
produced by a pulse generator 310 to a brain region into which an
exogenous stem cell is transplanted.
[0046] The pulse generator 310 may be implantable as shown for the
device 10 in FIG. 2. An implantable pulse generator system 300
includes an implantable pulse generator 310, such as Medtronic's
Model 7425 Itrel or Model 7427 Synergy. Typically, the implantable
pulse generator 310 will be electrically coupled to one or more
leads 320. Suitable leads 320 are known and can typically be
purchased with implantable pulse generators 310. Examples of
suitable leads 320 include Medtronic's Pisces leads, Resume leads
and other custom builds. The one or more leads 320 may be
positioned to apply an electrical signal produced by the
implantable pulse generator 310 to a brain region into which an
exogenous stem cell is transplanted.
[0047] A pulse generator 310, whether or not it is implantable, may
be programmed to adjust electrical signal parameters such as pulse
width, frequency, amplitude, polarization, and duration. A
physician or other person skilled in the biomedical arts with
respect to neurostimulation will understand that the parameters may
be optimized to achieve an electrical signal having desired
properties. The parameters and the location of the application of
the electrical signal may be varied to optimize therapeutic effect.
In an embodiment, an electrical signal having a voltage of between
about 1 mV to about 10 mV, a frequency of about 1 Hz to about 1000
Hz, and a pulse width of about 1 .mu.sec to about 500 .mu.sec is
applied to a CNS region to promote the proliferation,
differentiation, migration or integration of a stem cell.
[0048] Delivery of Therapeutic Agent
[0049] In an embodiment of the invention, one or more stem cell
enhancing agents may be administered to a CNS region of a subject.
The CNS region may be, e.g., a brain region in which an exogenous
stem cell is transplanted, a brain region containing damaged
nervous tissue, a brain region neurons from a brain region
containing damaged nervous tissue are predicted to send
projections, and the like. It will be understood that therapeutic
agents in addition to stem cell enhancing agents may also be
administered. The additional therapeutic agents may be beneficial
for treating a disease associated with loss of neuronal
function.
[0050] Referring to FIG. 2, a system for delivering a therapeutic
agent to a brain region of a subject is shown. The device 20
comprises a pump 40, a reservoir 12 for housing a composition
comprising a therapeutic agent, such as a growth factor, and a
catheter 38 having a proximal portion 35 operably coupled to the
pump 40 and an infusion section 39 adapted for infusing the
composition to the brain region of the subject. The device 20 may
be an implantable pump, as shown regarding the device 10 in FIG. 2,
or may be an external pump. The device 20 may have a port 34 into
which a hypodermic needle can be inserted to inject a quantity of
therapeutic agent into reservoir 12. The device 20 may have a
catheter port 37, to which the proximal portion 35 of catheter 38
may be coupled. The catheter port 37 may be operably coupled to
reservoir 12. A connector 14 may be used to couple the catheter 38
to the catheter port 37 of the device 20. The device 20 may contain
a microprocessor 42 or similar device that can be programmed to
control the amount of fluid delivery. The device may take the form
of Medtronic's SynchroMed EL or SynchroMed II infusion pump
system.
[0051] It will be understood that a therapeutic agent may be
administered to a brain region without use of a pump system 20.
[0052] Stem Cell Enhancing Agent
[0053] In an embodiment of the invention, one or more stem cell
enhancing agent may be administered in addition to a stimulation
signal. As used herein, a "stem cell enhancing agent" is an agent
that alone or in combination with another stem cell enhancing agent
or an electrical signal increases the likelihood that a stem cell
will migrate, proliferate, differentiate, integrate or release a
factor that may result in a neural cell migrating, proliferating,
differentiating, or integrating. Stem cell enhancing agents are
chemical compounds and may be small molecule chemical agents;
nucleic acids; including vectors, small inhibitory RNA, ribozymes,
and antisense molecules; polypeptides, and the like. While some
stem cell enhancing agents may affect the ability of a cell to
selectively proliferate, differentiate, migrate, or integrate, it
will be understood that many stem cell enhancing agents will affect
the ability of a cell to undergo a combination of more than one of
proliferate, differentiate, migrate and integrate. Accordingly, a
discussion of a stem cell enhancing agent as an agent that, e.g.,
promotes proliferation does not necessarily indicate that the agent
may not also promote one or more of differentiation, migration, and
integration. It will also be understood that a stem cell enhancing
agent may differentially affect proliferation, differentiation,
migration, and integration based upon the location in which the
agent is administered.
[0054] A stem cell enhancing agent may be a growth factor. Any
growth factor capable of repairing damaged neural tissue and/or
promoting neurogenesis may be administered. Exemplary suitable
growth factors include glial-derived neurotrophic factor (GDNF),
brain-derived neurotrophic factor (BDNF), fibroblast growth factor
(FGF), vascular endothelial growth factor (VEGF), nerve growth
factor (NGF), neurotrophin (NT), transforming growth factor (TGF),
ciliary neurotrophic factor (CNTF), epidermal growth factor (EGF),
insulin-like growth factor (IGF), stromal cell factor (SCF), notch,
heparan sulfate proteoglycans (HSPGs) and growth factors within
these classes such as, for example, NT-3, IGF-1, FGF-2, SCF-1 and
TGF-alpha. More than one growth factor may be administered. Each
growth factor may be administered in the same brain region or may
be administered in different locations. Any amount of a growth
factor may be administered. Preferably, an amount of a growth
factor capable of promoting stem cell proliferation,
differentiation, migration, or integration, when administered alone
or in combination with stimulation and/or additional therapeutic
agents, is administered. It will be understood that that the
efficacy of a growth factor may be enhanced by a cofactor. For
example, administration of cofactor cystatin C and IGF may enhance
the efficacy of FGF-2. In an embodiment of the invention, daily
doses of growth factors administered are in the range of about 0.5
micrograms to about 100 micrograms. For specific daily dose ranges
for NGF, BDNF, NT-3, CNTF, IGF-1, and GDNF that may be
administered, see U.S. Pat. No. 6,042,579, which is incorporated
herein by reference in its entirety.
[0055] Any growth factor may be administered. Some growth factors
may be referred to in the art as mitogens. In addition to the
growth factors listed above, other mitogens suitable for use in
accordance with the teachings of this disclosure include bone
morphogenic proteins (BMP), noggin, erythropoietin, and leukemia
inhibitory factor (LIF).
[0056] A growth factor or other stem cell enhancing agent may be a
chemoattractant agent. A chemoattractant agent is an agent that
directs a migrating cell to a particular region or an agent that
directs neuronal projections to a particular agent. Examples of
chemoattractant agents include stromal-cell-derived factor (SCF-1),
fractalkine, growth related oncogene alpha (GRO-.alpha.), IL-8,
MIP-1a, MIP-1b, MCP-1, MCP-2, MCP-3, GRO-a, GRO-b, GRO-g, RANTES,
and eotaxin
[0057] A stem cell enhancing agent may be an agent that inhibits
factors that prevent extensive cell replacement. Such agents
include an anti-nogo antibody, a p75ntr antagonist, a Rho-kinase
inhibitor, and a nogo-66 receptor antagonist.
[0058] A stem cell enhancing agent may include agents that increase
the likelihood that a neuron will undergo an action potential. Such
agents include glutamate receptor agonists, such as LY 354740 or
5-dihydroxyphenylglycine (DHPG) and GABA receptor antagonists, such
as CGP56433A or bicuculline.
[0059] Other neurotransmitters and agonists of their receptors that
may be useful for promoting the proliferation, differentiation,
migration, or integration of a stem cell include norepinepherine,
acetylcholine, dopamine, serotonin, and the like.
[0060] In an embodiment, a stem cell enhancing agent is a
transcription factor. Exemplary transcription factor include Pax6,
EMX2, SHH, a member of the NeuroD family, a member of the CREB
family, c-fos, myocyte enhancer factor-2 (MEF-2) and basic
helix-loop-helix (bHLH) transcription factors.
[0061] Exogenous Stem Cells
[0062] In an embodiment of the invention, an exogenous stem cell is
transplanted in the CNS of a subject at a location comprising
damaged nervous tissue. Any exogenous stem cell capable of forming
a mature nervous cell, such as a neuron or a glial cell, may be
transplanted into the subject. Exogenous stem cells may be isolated
using any known or future developed technique. For example, a stem
cell may be isolated from an embryo, from a tissue or from an
organ, including skin, and may be considered an embryonic stem cell
or an adult stem cell. Conversely, an established stem cell line
may be used.
[0063] Transplanted cells or grafts may be derived from auto-,
alla- or xeno- graphic sources. Transplanted or grafted cells for
brain tissue can be chosen from the group consisting of: adult
fibroblasts, fetal fibroblasts, adult smooth muscle cells, fetal
smooth muscle cells, endothelial cells, and skeletal myoblasts,
embryonic cells, cord blood cells, adult stem cells of any organ
such as brain, liver, heart, or bone marrow. Procedures for
isolation of these cell types are known in the field and described
elsewhere.
[0064] Exogenous stem cells may be introduced into a region of a
subject's CNS comprising damaged nervous tissue using any known or
future developed method. For example, exogenous stem cells may be
introduced by direct injection, injection through a catheter, and
the like.
[0065] An exogenous stem cell introduced into a region of a
subject's CNS may or may not comprise an electrically responsive
nucleic acid construct.
[0066] Ex Vivo Construction of ERP Stem Cells
[0067] In an embodiment, an exogenous stem cell comprising an
electrically responsive nucleic acid construct is introduced into a
region of a subject's CNS containing damaged nervous tissue. The
electrically responsive nucleic acid construct comprises an
electrically responsive promoter (ERP) and a target gene. The
target gene may encode a gene product that promotes the
proliferation, differentiation, migration, or integration of a stem
cell. For example, the target gene may encode CNTF, GDNF, BDNF,
FGF, VEGF, NGF, TNB, NT-3, TGF-alpha, TGF-beta, EGF, IGF-1, NT-4,
NT-5, EGF, CNTF, SCF, c-fos, NeuroD2, pax6, emx2, SHH, noggin, IL-3
FL, PDGF, FL, Tpo, IL-6 IL-11, or an active derivative or fragment
thereof. The nucleic acid construct may comprise more than one
target gene. Alternatively, more than one nucleic acid construct
may be introduced into an exogenous stem cell.
[0068] Nucleic acid constructs comprising ERPs can be introduced
into stem cells ex vivo in any known or future developed manner.
For example, such constructs may be introduced as described in WO
02/49669, which patent application is incorporated herein by
reference in its entirety. In WO02/49669, Schu et al. have
demonstrated that ERPs can be introduced into primary and secondary
cells of mammalian origin and that ERP promoters can be stably
integrated and operably linked to an exogenous genes using a wide
variety of vectors.
[0069] The generation of different specialized cell types of the
mammalian organism requires the establishment of diverse gene
expression patterns that characterize the individual cell types.
These patterns are formed through the combinatorial action of
transcriptional regulatory proteins, some of which have the
capacity to direct multipotent stem cells to assume a specific
developmental fate. For example PU.1 which commits multipotent
hematopoeietic cells to the myeloid lineage and C/EBP.alpha. which
can instruct progenitor cells to differentiate into adipocytes,
neutrophil granulocytes and eosinophils (Nerlov, C. and Grav, T.
(1998); Nerlov, C et al., 1998).
[0070] In an embodiment, neurologic factors are produced from
neural cells. Neural cells may be transfected in vivo or ex-vivo
with the relevant gene under control of an electrically responsive
promoter. Where neural cells are transfected ex-vivo they are then
transplanted into the desired site in the neural tissue. Within the
range of transplanted neural cells, include mature neuronal cells,
glial cells (e.g., astrocytes, oligodendrocytes), as well as neural
stem cells and the like.
[0071] An advantage to the use of ERP transfected primary or
cultured cells of the present invention is that the number of cells
required may be reduced and location of their delivery can be
specified. Further, the proliferation, differentiation, migration
and integration of the exogenous cell may be controlled by the
location of electrodes and the period of electrical stimulation.
Additionally, the exogenous cells may be controlled by the location
of the catheter delivering a therapeutic agent to encourage the
proliferation, differentiation, migration and integration of said
cells.
[0072] In its simplest mode, to stimulate the electrically
responsive elements within the cells of a patient, one would simply
turn on the electrical signal generating device. Programming would
be desired to be sure the amplitude of the electrical stimulation
was sufficient to be turning on the gene. The appropriate amplitude
would be determined as the lowest amplitude or 2.times., 3.times.,
4.times. or 5.times. the lowest amplitude, or as the case may be
that elicits a therapeutic outcome. In the absence of a detectable
therapeutic result, a pacing amplitude may be set using an assay
for the generated protein, or empirically using in vitro data on
the amplitude versus distance from the cell to affect
stimulation.
[0073] One or more electrically responsive construct may be
transfected into an exogenous cell to be transplanted into a CNS
region comprising damaged nervous tissue. Alternatively, different
cells may be transfected with different constructs. The different
constructs may contain ERPs that can be turned on when subjected to
electrical signals comprising different parameters. Any known or
future discovered or developed ERPs sensitive to various
stimulation parameters may be used.
[0074] Brain Region with Damaged Tissue
[0075] In an embodiment of the invention, an electrical signal or a
stem cell enhancing agent may be applied to a region of a brain
having damaged neural tissue or damage to the glial cells. A
therapy (i.e., electrical stimulation signal or a stem cell
enhancing agent) may be applied to any brain area having damaged
neural tissue in which exogenous stem cells have been
transplanted.
[0076] Damaged neural tissue may arise from a genetic source, a
disease, and/or a trauma. Damaged neural tissue may result from a
neruodegenerative disease, such as Parkinson's disease and
Alzheimer's disease. In Parkinson's disease, damage neural tissue
may be found in the substantia nigra. In Alzheimer's disease,
damaged neural tissue may be found in the basal forebrain,
particularly the nucleus basalis of meynert, or the hippocampus,
specifically the CA1 region. In a condition such as spinal cord
injury, it may be desirable to administer a therapy and exogenous
stem cells intrathecally at or near the level of the injury.
Damaged neural tissue will be readily identifiable to a physician
or other persons skilled in the biomedical arts.
[0077] One exemplary therapy includes the administration of the
growth factor, TGF-alpha, at a dose and rate sufficient to
encourage proliferation, differentiation, migration, or integration
of an exogenous transplanted stem cell. A suggested rate is in the
range from about 0.2 .mu.l/day to about 24 .mu.l/day. A suggested
dose is in the range from about 0.1 mg/ml to about 100 mg/ml.
[0078] Another exemplary therapy includes the administration of
noggin and BMP to a damaged brain region into which exogenous stem
cells have been transplanted. Temporally and spatially controlled
administration of BMP and noggin may be achieved using a device(s)
as described herein or as known in the art. Exogenous noggin may be
delivered to the exogenous stem cells to promote neuronal
differentiation whereas exogenous BMP may be delivered to promote
glial differentiation.
[0079] Another exemplary therapy includes applying an electrical
signal to promote the expression of a gene product in the area of
the damaged tissue at parameters sufficient to encourage the
proliferation, differentiation, migration or integration of the
exogenous stem cells. For example, the expression of c-fos,
neuroD2, nogging, or various other stem cell enhancing agents may
be encouraged. Electrical signal parameters may be in the range
from, e.g., about 1 Hz to about 150 Hz, about 90 .mu.sec to about
500 .mu.sec, and about 0.1 V to about 10V.
[0080] In addition to delivering a stem cell enhancing agent to a
CNS region comprising damaged neural tissue, it may be desirable to
deliver such agents intraventricularly or intrathecally. Such
non-targeted delivery of therapy may broadly encourage the
proliferation, differentiation, migration, or integration of the
exogenous stem cells.
[0081] Brain Regions to which Neurons Project
[0082] In an embodiment, therapy is delivered to a CNS region in
which neurons are predicted to project. More particularly, therapy
may be administered to a region where differentiated neuronal stem
cells are expected to project to facilitate the newly developed or
existing yet damaged neurons to make the appropriate neuronal
connections.
[0083] Regions to which neurons are expected to send projections
are known to those of skill in the art. For example, neurons of the
substantial nigra send projections to the putamen. Accordingly to
treat Parkinson's disease, it may be desirable to encourage newly
integrated or differentiated neurons or damaged neurons of the
substantia nigra to send projections to the putamen. This may be
accomplished by delivering electrical signal, a stem cell enhancing
agent, or a combination thereof to the putamen to encourage the
neurons of the substantia nigra to make appropriate connections
with neurons of the putamen.
[0084] In another example, a group of cholinergic neurons in the
basal forebrain project to the neocortical and medial temporal
regions. In Alzhiemer's disease this group of cholinergic neurons
are selectively damaged, resulting in severe impairment of
learning. It may be desirable to encourage newly integrated or
differentiated neurons of the basal forebrain to send projections
to the neocortical and medial temporal regions. Furthermore, it may
be desirable to encourage the newly established neuronal cell to
produce acetylcholine to restore the function of the cholinergic
transmission in the brain area. This may be accomplished by
delivering electrical signal, a stem cell enhancing agent, or a
combination thereof to the neocortical and the medial temporal
regions to encourage the neurons of the basal forebrain to make
appropriate connections with neurons of the neocortical or medial
temporal region. Likewise, replacement strategy may be achieved by
delivering electrical signal, a stem cell enhancing agent, or a
combination thereof to the basal forebrain to encourage the neurons
of the neocortical and medial temporal regions to make appropriate
connections with neurons of the basal forebrain.
[0085] Other neurotransmitter systems are selectively disrupted by
the Alzheiemer's disease process in a manner similar to the
cholinergic system. In another example, the cortically projecting
norepinephrine neurons of the locus coeruleus and the raphe neurons
of the dorsal and central raphe nuclei are disrupted. It may be
desirable to encourage newly differentiated or integrated or
damaged neurons of the locus coeruleus and the raphe nucleus to
send projections to the cortex. This may be accomplished by
delivering electrical signal, a stem cell enhancing agent, or a
combination thereof to the locus coeruleus and the raphe
nucleus.
[0086] In another example, axons of the neurons in the spinal cord
may traverse some distance in the spinal cord on their way to
project to a particular spinal cord level. During spinal cord
injury, these axonal projections are damaged, resulting in
impairment of sensory and movement functions and often paralysis.
It may be desirable to encourage the newly integrated or
differentiated neurons of one spinal cord level to send projections
to the other spinal cord level in a manner that will result in an
the repair of axonal projections over the injured area.
[0087] Therapy
[0088] In various embodiments of the invention, transplanted
exogenous stem cells and therapy may be delivered to one or more
CNS regions to treat a disease associated with loss of neuronal
function. Exogenous stem cells are preferably transplanted into a
CNS region comprising damaged nervous tissue. One or more
therapies, e.g. electrical signal and stem cell enhancing agent,
may be delivered to, e.g., the damaged brain region into which the
exogenous cells are transplanted or a region to which neurons from
the damaged CNS region are predicted to project. In various
embodiments, a stem cell enhancing agent and an electrical signal
are delivered to the brain region into which the exogenous stem
cells are transplanted. If the exogenous stem cell comprises an
electrically responsive genetic construct an electrical signal is
preferably delivered to the brain region into which the exogenous
cells are transplanted.
[0089] Referring to FIG. 5, an exemplary embodiment useful for
treating Parkinson's disease is shown. Exogenous stem cells, which
may or may not contain an electrically responsive genetic
construct, are implanted into the substantia nigra at step 1. A
first therapy delivery element 5 having a therapy delivery region
is implanted into the brain of the subject such that the therapy
delivery region is positioned in or near the substantia nigra. At
step 2, therapy is applied to the substantia nigra to promote
proliferation, differentiation, migration, or integration of the
exogenous stem cell. A second therapy delivery element having a
delivery region is implanted such that the delivery region is
positioned in or near the putamen. At step 3, therapy is delivered
to the putamen to encourage projections of neurons from the
substantia nigra to the putamen. The projections may be from
existing neurons or from neurons derived from the exogenous stem
cells. The first and second therapy elements may be catheters,
leads, or elements comprising both infusion sections and
electrodes, or combinations thereof.
[0090] Referring to FIG. 6, an overview of a method of treating a
disease associated with a loss of neuronal function is shown. As
shown in FIG. 6, an exogenous stem cell is transplanted into an
area of the CNS (1000). At 1010, an electrical signal is applied to
the area of the CNS into which the exogenous cell was implanted. At
1020, a stem cell enhancing agent is applied to the region into
which the exogenous cell was implanted. The stem cell enhancing
agent may serve to promote proliferation, differentiation,
migration, or integration of the exogenous stem cell.
[0091] FIG. 7 depicts an overview of a method of treating a disease
associated with a loss of neuronal function. The method of depicted
in FIG. 7 is similar to that of FIG. 6. In FIG. 7, an additional
step of transfecting the endogenous stem cell with an electrically
responsive nucleic acid construct is shown at 1030. The
electrically responsive nucleic acid construct may comprising a
gene encoding a gene product capable of promoting proliferation,
differentiation, migration, or integration of the exogenous stem
cell. The application of the electrical signal (1010) may control
the expression of the gene product.
[0092] FIG. 8 depicts a method of achieving the treatment protocol
described in FIG. 6. An electrode of a lead may be positioned in an
area of the brain comprising damaged nervous tissue (1040).
Exogenous cells may be transplanted into the damaged CNS region
(1000) before of after the lead is implanted and the electrode is
positioned (1040). At 1050, a catheter is implanted and a delivery
region of the catheter is positioned into an area of the brain
comprising damaged nervous tissue (1050). Exogenous cells may be
transplanted into the damaged CNS region (1000) before of after the
catheter is implanted and the delivery region is positioned (1050).
At 1060, an electrical signal is applied via the electrode to
promote proliferation, differentiation, migration, or integration
of the exogenous stem cell. At 1070, a stem cell enhancing agent is
applied via the delivery region to promote proliferation,
differentiation, migration, or integration of the exogenous stem
cell.
[0093] Referring to FIG. 9, an overview of a method of treating a
disease associated with a loss of neuronal function is shown. As
shown in FIG. 6, an exogenous stem cell is transplanted into an
area of the CNS (1000). At 1010, an electrical signal is applied to
the area of the CNS into which the exogenous cell was implanted. At
1020, a stem cell enhancing agent is applied to the region into
which the exogenous cell was implanted. The stem cell enhancing
agent may serve to promote proliferation, differentiation,
migration, or integration of the exogenous stem cell. At 1080, a
therapy (i.e., an electrical signal or a stem cell enhancing agent)
is delivered to a second region of the CNS to which neurons from
the damaged CNS region are predicted to project. FIG. 10 shows the
additional step of delivering a stem cell enhancing agent
intrathecally or intraventricularly to enhance the therapy
(1090).
[0094] FIG. 11 depicts an overview of a method for treating a
disease associated with loss of neuronal function. At 1100, an
exogenous stem cell is transplanted to an area of the CNS
comprising damaged nervous tissue. At 1100, a first therapy is
applied to the area of the CNS comprising damaged nervous tissue.
The therapy may serve to promote the proliferation,
differentiation, migration, or differentiation of the exogenous
stem cell. At 1120, a second therapy is applied to a second CNS
region to which neurons from the damaged CNS region are predicted
to project. The therapy may serve to promote the projections to
ensure proper connections are made. FIG. 122 shows an additional
step of delivering a stem cell enhancing agent intrathecally or
intraventricularly to enhance therapy (1130).
[0095] Other methods and combinations of steps shown in FIGS. 6-12
are contemplated. It will be understood that various steps as shown
in FIGS. 6-12 may occur in any logical order and applications of
various therapies can occur at the same or different times.
[0096] All printed publications, such as patents, patent
applications, technical papers, and brochures, cited herein are
hereby incorporated by reference herein, each in its respective
entirety. As those of ordinary skill in the art will readily
appreciate upon reading the description herein, at least some of
the devices and methods disclosed in the patents and publications
cited herein may be modified advantageously in accordance with the
teachings of the present invention.
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